Hypothyroidism and hyperthyroidism: Understanding the differences

If your body’s metabolism is an orchestra, the thyroid gland is the conductor.

The thyroid is a butterfly-shaped organ at the front of your throat that produces important hormones. These hormones travel all over your body to regulate functions such as your heart rate, breathing, muscle strength, body temperature, body weight, cholesterol, and your central nervous system. Since your thyroid has an effect on virtually every organ in your body, if it’s not functioning properly, you’re going to feel unwell.

As many as 25 million Americans have a problem with their thyroid, such as hypothyroidism or hyperthyroidism. “Many people with thyroid issues don’t know they have a problem,” said Wynn Htun, M.D., an endocrinologist at Geisinger Wyoming Valley Medical Center in Wilkes-Barre. “A lot of the symptoms seem like something else, or may be mistaken for aging and other illnesses.”

Hypothyroidism: Everything slows down

“Thyroid hormone levels are controlled by a feedback loop between the thyroid and two glands in your brain called the hypothalamus and the pituitary,” said Dr. Htun. “The hypothalamus and pituitary monitor levels of thyroid hormones in the blood, and tell your thyroid to make more or less of them.”

Hypothyroidism, or underactive thyroid, accounts for the majority of imbalances people experience with their thyroid gland. When levels of two key thyroid hormones – called thyroxine (T4) and triiodothyronine (T3) – are too low in your blood, everything in your body starts to slow down. You may experience symptoms such as:

Fatigue

Forgetfulness

Dry skin, dry hair and brittle nails

Slowing of your bowels or constipation

Weight gain

Muscle cramps

Reduced menstrual flow

Depression

The most common cause of hypothyroidism is an autoimmune disease called Hashimoto’s thyroiditis. This disease causes the immune system to mistakenly attack a healthy thyroid gland. As a result, the thyroid becomes inflamed and is no longer able to make enough thyroid hormones.

“Hypothyroidism can be effectively treated with a synthetic thyroid replacement hormone,” said Dr. Htun. “Your doctor will monitor your hormone levels on an ongoing basis and make adjustments, but most patients start to see an improvement about a week after starting treatment.”

Hyperthyroidism: Everything speeds up

Hyperthyroidism creates the opposite problem: The thyroid is overactive and produces more thyroid hormones than the body needs. As a result, the organs and systems in your body that these hormones interact with start to speed up, creating symptoms such as:

Weight loss

Difficulty concentrating

Feeling hot and sweating

Problems falling asleep

Anxiety, nervousness and irritability

Racing heart and palpitations

Changes in bowel habits and loose stools

The most common cause of hyperthyroidism is Grave’s disease, which is also an autoimmune disease. Grave’s disease causes the immune system to attack the thyroid, producing antibodies that bind to the surface of thyroid cells. These cells are then stimulated and overproduce thyroid hormones.

There are several treatments available for hyperthyroidism. Radioactive iodine can be used to shrink the thyroid gland. Anti-thyroid medications can reduce symptoms by preventing the thyroid from producing too many hormones. Surgery is also an option if you are pregnant or unable to tolerate other medical treatments.

“If you’re feeling unwell and experience any of the common symptoms of a thyroid problem, talk to your doctor,” said Dr. Htun. “Treatment is relatively simple and can help you get back to feeling like yourself again.”